Transcript for School Bookkeeper: Alleged Shooter Said 'He Was Going to Die'

We are joined, now, by that hero bookkeeper, antoinette tuff. Along with eric hines and clay haas with the police department. Thanks for your great work and presence of mind in that situation. Antoinette, let me begin with you. What went through your mind when you saw the young man walk in with a gun in your office? The safety of the students. And making sure nobody gets harmed. What did you say to him? At first, I thought it was a false alarm. And he allowed me to know it was not a false alarm. At that moment, you knew you were in danger. You knew the students were in danger. What did you do? He actually asked one of the teachers that was with me to go and let everyone know that this was not a false alarm. That he was here. And I began to speak with him. But at that time, he would not say anything. He just wanted me to know that he was not playing. And for me to call the news and also the police to let everyone know he was here. And at one point, he actually went out. Some shots were fired outside. And he came back into the office. And that's when there really was a dialogue. Yes. He went out the door several times. And then shot outside of the door and also did a shot inside of the school. That's when he began to tell him about yourself and your own struggles. Yes. I began to tell him some of my life and some of the things that was actually happening to me. And to get him to start talking with me and opening up. What did he say? He said that he hadn't taken his medication. And that he was going to die anyway. And that he was okay with dying. And that he was going to kill all of the police officers. And that he wanted me to know that he was not going to hurt me. And I told him, okay. And that, it was going to be okay. And you told him you loved him? Yes, I did. He said that no one loved him. And I told him that I loved him. And that it was going to be okay. We were going to get out safely. And I told him that if he just go ahead and surrender, since he didn't hurt anyone, that I would stay there with him until they came to get him. And so, I walked him through taking everything out of his pocket. Taking all of the magazines that he had loaded, all the additional weapons and everything that he had on him, out of the bag and put the bag on the counter. Along with everything else. How did you stay so composed in this situation? Through prayer. I prayed the whole time. And officer, while this is going on inside the office, you are scrambling outside and doing your best to get all those kids safe. Officer hines? We were outside. I was outside. And actually, I was able to listen in on the conversation, that she had with the police officer relaying that information, the exact location of the shooter. Where he was, what his demeanor was. And some of the actions he was doing inside the school, I was able to relay that over to detective hobbs on the other side of the school, formulating a plan to make entry. And detective hobbs, what happened next? Once we found out where he was located inside the school, actually gain entry through a side door at the school. And luckily, we had an officer that was family with the layout of the school. And I made it to the office, where he had the man on the ground to take him into custody. She did an amazing job, didn't she? Yes, he did. Outstanding. You all did. You saved a lot of lives yesterday. And we're all grateful for it. Thank you for your service. Thank you for joining us this morning. Thank you. Thank you, sir. Appreciate it. She did everything right. Her composure is miraculous. And antoinette is going back to work this morning. Everyday hero. Let's go to the news. Josh is resting that bad back.

This transcript has been automatically generated and may not be 100% accurate.

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